NH3-N Concentration Research Articles

Impacts of Protein and Energy Levels on Rumen Fermentation and Microbial Activity Under Different Incubation Temperatures

This study aimed to explore the effects of different incubation temperatures on ruminal fermentation and rumen microorganisms and determine the appropriate protein and energy levels to enhance microbial protein synthesis using an in vitro system. Rumen inoculum was collected from two fistulated Holstein heifers (trial 1: BW: 652.3 kg ± 25.2; trial 2: BW: 683.3 kg ± 30.2) and assessed using a closed-batch culture system. The experimental model employed a 2 × 5 factorial arrangement using incubation temperatures set to 39 and 41 °C, with protein levels set to 12.0, 13.5, 15.0, 16.5, and 18.0% of DM in trial 1 or with energy levels set to 2.4, 2.5, 2.6, 2.7, and 2.8 Mcal/kg of DM in trial 2. The data were analyzed using the MIXED procedure. The results showed increased (p < 0.05) NH3-N concentrations and total volatile fatty acids (TVFAs) with higher incubation temperatures, while the liquid-associated bacterial (LAB) amounts decreased (p < 0.05) in trials 1 and 2. The interaction between the energy level and incubation temperature affected (p < 0.05) the LAB protein levels in trial 2. Higher protein levels led to increased (p < 0.05) NH3-N and acetate concentrations, but it decreased (p < 0.05) the propionate percentage. Conversely, higher energy levels decreased (p < 0.05) the amount of acetate and increased the propionate concentration, altering the acetate-to-propionate ratio. However, no interaction involving TVFA and LAB was observed between the incubation temperature and the protein or energy levels. Changes in the NH3-N, TVFAs, and LAB protein amounts were observed under different incubation temperatures and energy levels. In conclusion, these findings provide insight into the metabolic adaptation under different ruminal temperatures and the impacts of dietary adjustments on rumen fermentation and microbial activity. However, there are limitations to replicating the complex physiological responses that occur within the whole body solely through in vitro experiments.

The Impact of Acute Ammonia Nitrogen Stress on Serum Biochemical Indicators and Spleen Gene Expression in Juvenile Yellowfin Tuna (Thunnus albacares)

The presence of ammonia nitrogen in water has a significant impact on the serum and spleen of fish, potentially leading to changes in substances such as proteins in the serum while also causing damage to the immune function of the spleen. To investigate the effects of ammonia nitrogen (NH3-N) stress on juvenile yellowfin tuna (Thunnus albacares), this study established three NH3-N concentrations, 0, 5, and 10 mg/L, denoted as L0, L1, and L2, respectively. Serum and spleen samples were collected at 6, 24, and 36 h. The effects of different NH3-N concentrations and exposure times on the physiological status of juvenile fish were investigated by analyzing serum biochemical indices and splenic gene expression. The results indicate that in the L1 group, the serum high-density lipoprotein cholesterol (HDL-C), triglycerides (TG), complement 3 (C3) and complement 4 (C4) levels, and acid phosphatase (ACP) activity showed a trend of initially increasing and then decreasing. In the L2 group, the serum low-density lipoprotein cholesterol (LDL-C), HDL-C, and C4 levels and ACP activity also displayed an initially rising and then declining trend, while TG, C3, and creatinine (CRE) levels and alkaline phosphatase (AKP) activity showed an upward trend. In the L1 group, glutathione peroxidase 1b (GPX1b), interleukin 10 (IL-10), interleukin 6 receptor (IL-6r), and tumor necrosis factor alpha (TNF-α) gene expression levels in the spleen exhibited a trend of first increasing and then decreasing. In the L2 group, IL-10, IL-6r, tumor necrosis factor beta (TNF-β), caspase 2 (casp2), and caspase 9 (casp9) gene expression levels in the spleen also showed an initial increase followed by a decrease. When NH3-N levels are below 5 mg/L, it is recommended to limit stress exposure to no more than 36 h for the juvenile fish. For concentrations ranging from 5 to 10 mg/L, stress should be strictly controlled to within 24 h. Exposure to high NH3-N levels may affect biochemical indicators such as serum lipid metabolism, immunity, and metabolism in juvenile fish, and may damage the expression of antioxidant, immune gene, and apoptosis factors in the spleen. This study aims to deepen our understanding of the effects of NH3-N on juvenile tuna, with the goal of establishing effective water quality monitoring and management strategies. This will ensure the quality of aquaculture water, reduce the harm caused by NH3-N to juvenile yellowfin tuna, and enhance aquaculture efficiency and product quality.

Dynamics of Fermentation Parameters and Bacterial Community in Rumen of Calves During Dietary Protein Oscillation

Dietary crude protein concentration oscillation can improve the nitrogen utilization efficiency of ruminants. However, little is known about the dynamic changes in microbiota and fermentation in the rumen of calves during the oscillation period. In this study, six calves were fed an oscillating diet at 2-day intervals, including a high-protein diet (HP) and a low-protein diet (LP). The rumen fermentation parameters, plasma urea-N concentration, and rumen bacterial diversity were characterized throughout the oscillation period. The concentrations of volatile fatty acids, NH3-N, and plasma urea-N in rumen changed significantly with an oscillating diet. The abundance of Prevotella_1, Selenomonadales, Succiniclasticum, Clostridiales, Ruminococcaceae, Lachnospiraceae, and Rikenellaceae_RC9_gut_group showed significant changes with diet. Prevotella_1 was positively correlated, and Lachnospiraceae_AC2044_group and Saccharofermentans were negatively correlated with NH3-N. The abundance of Amino Acid Metabolism, Metabolism of Other Amino Acids, and Glycan Biosynthesis and Metabolism pathways, annotated by bacterial functional genes, decreased when the diet changed from HP to LP. The abundance of the Carbohydrate Metabolism pathway increased after the two dietary changes. In conclusion, the plasma urea-N concentration was not as sensitive and quick to adapt to diet changes as the rumen fermentation parameters. Rumen bacteria were responsible for increasing the nitrogen utilization efficiency of calves fed an oscillating diet.

Effects of spent substrate of oyster mushroom (Pleurotus ostreatus) on ruminal fermentation, microbial community and growth performance in Hu sheep

IntroductionThe study aimed to evaluate the effects of Pleurotus Spent Mushroom Substrate (P.SMS) on the rumen microbiota, encompassing bacteria and fungi, as well as their interactions in Hu sheep.MethodsA total of forty-five 3-month-old Hu sheep were randomly assigned to five groups. Each group was fed diets in which whole-plant corn silage (WPCS) was substituted with P.SMS at varying levels: 0% (CON), 5% (PSMS5), 10% (PSMS10), 15% (PSMS15), or 20% (PSMS20).ResultsThe results indicated that higher proportions of P.SMS during the experimental period might have a detrimental effect on feed utilization efficiency, kidney function, and blood oxygen-carrying capacity. Notably, moderate levels of P.SMS, specifically below 15%, were associated with improvements in rumen NH3-N levels and absorption capacity. The results indicated that (1) PSMS20 exhibited a significantly higher feed-to-gain ratio compared to CON (P < 0.05); (2) PSMS15 showed a significantly higher NH3-N content than CON, PSMS5, and PSMS20. Additionally, PSMS10 and PSMS20 had elevated concentrations of NH3-N compared to CON and PSMS5 (P < 0.05); (3) The length and width of rumen papillae were significantly greater in PSMS20 compared to CON and PSMS5 (P < 0.05); (4) Creatinine levels were significantly higher in PSMS20 than in CON, PSMS5, and PSMS10 (P < 0.05); (5) By the conclusion of the experiment, hemoglobin concentration in PSMS20 showed a significant increase compared to CON (P < 0.05). Furthermore, the addition of P.SMS influenced microorganisms at both the phylum and genus levels: (1) At the phylum level, the prevalence of Patescibacteria was significantly lower in PSMS20 compared to the other groups; (2) PSMS15 exhibited significantly higher relative abundances of Basidiomycota compared to CON and PSMS10, while PSMS20 also demonstrated significantly higher relative abundances compared to CON (P < 0.05); (3) At the genus level, the prevalence of Candidatus_Saccharimonas in PSMS20 was significantly lower than in PSMS5, PSMS10, and PSMS15. Conversely, the prevalence of Phanerochaete in PSMS15 was notably higher than in CON and PSMS10, and it was also significantly elevated in PSMS20 compared to CON (P < 0.05); (4) Correlation analysis indicated no significant correlation between changes in the structure of bacterial and fungal communities.DiscussionConsidering these findings, a high percentage of P.SMS negatively impacted feed utilization efficiency, blood oxygen carrying capacity, and kidney function, while a moderate percentage of P.SMS promotes rumen absorption capacity, indicating that feeding 10% P.SMS is optimal.

Semi-Supervised Soft Computing for Ammonia Nitrogen Using a Self-Constructing Fuzzy Neural Network with an Active Learning Mechanism

Ammonia nitrogen (NH3-N) is a key water quality variable that is difficult to measure in the water treatment process. Data-driven soft computing is one of the effective approaches to address this issue. Since the detection cost of NH3-N is very expensive, a large number of NH3-N values are missing in the collected water quality dataset, that is, a large number of unlabeled data are obtained. To enhance the prediction accuracy of NH3-N, a semi-supervised soft computing method using a self-constructing fuzzy neural network with an active learning mechanism (SS-SCFNN-ALM) is proposed in this study. In the SS-SCFNN-ALM, firstly, to reduce the computational complexity of active learning, the kernel k-means clustering algorithm is utilized to cluster the labeled and unlabeled data, respectively. Then, the clusters with larger information values are selected from the unlabeled data using a distance metric criterion. Furthermore, to improve the quality of the selected samples, a Gaussian regression model is adopted to eliminate the redundant samples with large similarity from the selected clusters. Finally, the selected unlabeled samples are manually labeled, that is, the NH3-N values are added into the dataset. To realize the semi-supervised soft computing of the NH3-N concentration, the labeled dataset and the manually labeled samples are combined and sent to the developed SCFNN. The experimental results demonstrate that the test root mean square error (RMSE) and test accuracy of the proposed SS-SCFNN-ALM are 0.0638 and 86.31%, respectively, which are better than the SCFNN (without the active learning mechanism), MM, DFNN, SOFNN-HPS, and other comparison algorithms.

Impact of Inoculation with Pediococcus pentosaceus in Combination with Chitinase on Bale Core Temperature, Nutrient Composition, Microbial Ecology, and Ruminal Digestion of High-Moisture Alfalfa Hay

This study evaluated the effects of Pediococcus pentosaceus (PP) and chitinase combinations on the conservation and nutritive value of alfalfa high-moisture hay (HMH). P. pentosaceus [1012 colony forming unit/g fresh forage] combined with (g/tonne of fresh forage) 1.5 (PP + LC), 7.5 (PP + MC), or 15.0 (PP + HC) g of LANiHay01 chitinase (Exp. 1) or with LANiHay02 (PP + Fe; 1.5 g), LANiHay01 (PP + Pe; 1.5 g), or Sigma (PP + Si; 55 mg) chitinase/tonne (Exp. 2) were used in 2016. In 2017, PP was applied alone or in combination with LANiHay01 at 1.5 g (PP + LC) or 7.5 g (PP + MC) chitinase/tonne (Exp. 3 and 4). Deionized water and propionic acid (4.0 L/tonne of fresh forage in Exp. 1 and 2 and at 6.0 L/tonne of fresh forage in Exp. 3 and 4) were applied as neutral (CON) and positive control (CON+), respectively. The maximum temperature (r2 = 0.66) and NH3-N concentration (r2 = 0.80) of the HMH were positively related to total microbial populations. PP + MC had lower (p ≤ 0.05) yeast and mold counts than CON in Exp. 3 and 4 while the neutral detergent fiber degradability was greater (p < 0.01) for PP + MC and PP + LC than CON in Exp. 1 and 3, respectively. P. pentosaceus in combination with chitinase has the potential in conserving the nutrient quality of alfalfa HMH.

Effects of water extracts of Artemisia annua L. on rumen immune and antioxidative indexes, fermentation parameters and microbials diversity in lambs

The present study investigated the effects of water extracts of Artemisia annua L. (WEAA) on rumen immune and antioxidative indexes, fermentation parameters and microbial diversity in lambs. A total of 32 3-month-old Dorper × Han female lambs having comparable body weights (24±0.09 kg) were selected and were randomly assigned to four treatments, with eight repetitions for each treatment. The basal diet, consisting of 45% concentrate and 55% forage, was solely provided to the control group. For the other treatment groups, the basal diet was supplemented with WEAA at dosages of 500, 1000, and 1500 mg/kg diet, respectively. Rumen tissue samples were collected for the analysis of immune and antioxidative parameters, as well as related gene expression. Rumen fluid samples were collected to assess rumen fermentation parameters on days 30 and 60 and to evaluate the microbiota on day 60. Results showed that WEAA supplementation linearly or quadratically increased the content of sIgA, IL-4, IL-2 and the gene expression level of MyD88, IκB-α, IL-4, COX-2, iNOS in rumen tissue (p < 0.05), as well as the bacteria negatively associated with IL-6 (g_ [Eubacterium]_cellulosolvens_group). Furthermore, the addition of WEAA linearly or quadratically increased rumen T-SOD, GSH-Px (p < 0.05) and the gene expression level of Nrf2, SOD2, GSH-Px, HO-1 (p < 0.05), and decreased the rumen concentration of malondialdehyde (MDA) and gene expression level of Keap1 (p < 0.05), as well as the bacteria positively associated with T-AOC, T-SOD and GSH-Px (g_Lachnospiraceae_NK3A20_group, g_Saccharofermentans, g__Marvinbryantia, g_unclassified_f_Eggerthellaceae). The supplementation of WEAA caused the concentration of microprotein (MCP), total volatile fatty acids (TVFA), propionate to increase either linearly or quadratically, while reducing the concentration of NH3-N and the acetate/propionate ratio (A:P) in rumen fluid (p < 0.05). The addition of WEAA linearly or quadratically increased the abundance of Actinobacteriota, Cyanobacteria and Lachnospiraceae_NK3A20_group (p < 0.10), and g__Lachnospiraceae_NK3A20_group, g_Saccharofermentans, g_Marvinbryantia, g_Bifidobacterium were significantly abundant as specific microflora in the 1000 mg/kg WEAA supplementation group. In conclusion, dietary inclusion of 1000 mg/kg WEAA improved the rumen immune function, antioxidant status, rumen fermentation, and composition of rumen microbes in lambs.

Spatial distribution of bacterial communities driven by environmental factors in the sediment of Lateolabrax japonicus ponds

Dynamic changes of bacterial communities in the sediment are very important for preventing diseases and water quality in aquaculture ponds. In this study, bacterial communities in the sediment of Sea perch Lateolabrax japonicus, an important farmed fish in China, ponds were studied using 16S rRNA Illumina sequencing and functional gene array. At the phylum level, Pseudomonadota, Actinomycetota and Chloroflexota were the dominant species. The bacterial community composition was different in spatial variation. Among the environmental factors, the concentration of nitrogen related factors (TN, NO3−-N NH3-N, NO2−N) and total organic carbon was the main impact on the composition of bacterial community, especially denitrifying bacterial community. Nitrifying and denitrifying bacteria accounted for 4.81 %, and bacteria related to nitrogen cycle accounted for 18.36 %. Higher diversity of bacteria in healthy fish pond than that of the diseased fish pond. In the diseased fish pond, lower abundance of Nitrosospira and higher abundance of Nitrobacter were found, and the contents of NH3-N, NO2−-N and total organic carbon were significantly higher. This study would help to reveal that microbial community structure could reflect the health of cultured animal and surroundings, and it could provide a theoretical reference for the healthy environments in the sediment of Sea perch ponds in South China.

Sardine Processing Waste: Biological Treatment Strategies and Their Implications

This study explores sustainable methods for Sardine Processing Waste (SPW) valorization. Two approaches were investigated: (a) SPW microbial pretreatment adding Saccharomyces cerevisiae or Bacillus sp. in a two-stage anaerobic digestion (AD) for enzyme and biomethane production and (b) a single-stage AD without SPW pretreatment. Both S. cerevisiae and Bacillus sp. secreted proteases (0.66 and 0.58 U mL−1, respectively) and lipases (3.8 and 4.3 U mL−1, respectively) during hydrolysis, thus reducing viscosity (2.8 and 2.9 cP, respectively) compared with the untreated SPW (4.1 cP). Biomethane production was higher in the single-stage AD (1174 mL CH4 g−1 VS−1) when compared with the two-stage AD (821.5 and 260 mL CH4 g−1 VS−1 with S. cerevisiae and Bacillus sp., respectively). S. cerevisiae addition enhanced SPW degradation as implied by VS and sCOD values (70 and 84%, respectively), but this also resulted in a higher toxicity due to a three-fold increment in NH4-N content, reducing methanogen activity. This research demonstrates the innovative application of S. cerevisiae, a common bread-making yeast, in the biotechnological enhancement of SPW hydrolysis. Non-genetically engineered S. cerevisiae not only co-produced proteases and lipases but also significantly improved solubilization, degradation, and viscosity reduction, thereby rendering the yeast a key player in solid fish waste valorization, beyond its traditional applications.

Hybridization promotes growth performance by altering rumen microbiota and metabolites in sheep.

Hybridization can substantially improve growth performance. This study used metagenomics and metabolome sequencing to examine whether the rumen microbiota and its metabolites contributed to this phenomenon. We selected 48 approximately 3 month-old male ♂Hu × ♀Hu (HH, n = 16), ♂Poll Dorset × ♀Hu (DH, n = 16), and ♂Southdown × ♀Hu (SH, n = 16) lambs having similar body weight. The sheep were fed individually under the same nutritional and management conditions for 95 days. After completion of the trial, seven sheep close to the average weight per group were slaughtered to collect rumen tissue and content samples to measure rumen epithelial parameters, fermentation patterns, microbiota, and metabolite profiles. The final body weight (FBW), average daily gain (ADG), and dry matter intake (DMI) values in the DH and SH groups were significantly higher and the feed-to-gain ratio (F/G) significantly lower than the value in the HH group; additionally, the papilla height in the DH group was higher than that in the HH group. Acetate, propionate, and total volatile fatty acid (VFA) concentrations in the DH group were higher than those in the HH group, whereas NH3-N concentration decreased in the DH and SH groups. Metagenomic analysis revealed that several Prevotella and Fibrobacter species were significantly more abundant in the DH group, contributing to an increased ability to degrade dietary cellulose and enrich their functions in enzymes involved in carbohydrate breakdown. Bacteroidaceae bacterium was higher in the SH group, indicating a greater ability to digest dietary fiber. Metabolomic analysis revealed that the concentrations of rumen metabolites (mainly lysophosphatidylethanolamines [LPEs]) were higher in the DH group, and microbiome-related metabolite analysis indicated that Treponema bryantii and Fibrobacter succinogenes were positively correlated with the LPEs. Moreover, we found methionine sulfoxide and N-methyl-4-aminobutyric acid were characteristic metabolites in the DH and SH groups, respectively, and are related to oxidative stress, indicating that the environmental adaptability of crossbred sheep needs to be further improved. These findings substantially deepen the general understanding of how hybridization promotes growth performance from the perspective of rumen microbiota, this is vital for the cultivation of new species and the formulation of precision nutrition strategies for sheep.

The Effect of Humic Acid Supplementation on Selected Ruminal Fermentation Parameters and Protozoal Generic Distribution in Cows

The objective of this study was to examine the effect of humic acid (HA) supplementation on the rumen fermentation and protozoal community in the rumen. For this purpose, four ruminally cannulated Simmental cows were randomly assigned in a replicated 4 × 4 Latin square design experiment to study the effect of HA dietary supplementation on feed utilization, rumen fermentation, and protozoal community for 84 days. The basal diet (BD) was composed of meadow hay (68.2% of dry matter [DM]), maize silage (17% of DM), and granulated feed mixture (14.9% of DM). There were four treatments, including the BD without additives (control diet, H0), the BD supplemented with 50 g HA/cow/day (H50 treatment), the BD supplemented with 100 g HA/cow/day (H100 treatment), and the BD supplemented with 200 g HA/cow/day (H200 treatment). HA supplementation did not affect the total or individual volatile fatty acid concentrations, the total protozoa, or the ruminal pH. However, HA at the dosage of 50 g/cow/day increased the NH3-N concentration and fecal nitrogen compared to the control (p < 0.001). HA supplementation also significantly impacted the abundance of individual protozoal genera in the rumen. The results of this study suggest that HA has potential in ruminants as a natural feed additive and may play a role in nitrogen metabolism and stabilizing the protozoal community without adverse effects on rumen fermentation.

PSXIII-26 Effects of Lentilactobacillus lactis and Lentilactobacillus buchneri on fermentation and aerobic stability in corn grain silages

Abstract The inclusion of corn grain silages (early-harvest and reconstitute grain) in the diets has gained wide acceptance in the last decade among Brazilian farms. Thus, reducing losses in these silages is one of the main goals. The objective of this study was to evaluate the effects of an inoculant containing Lentilactobacillus lactis O224 and Lentilactobacillus buchneri LB1819 on fermentation, microbial counts, and aerobic stability in reconstituted corn grain (RCG) and high-moisture corn (HMC). Two experiments were carried out, which tested the inclusion of no additive (CON) and the addition of L. lactis and L. buchneri. For both trials, the inoculant was added at a theoretical rate of 1.5 x 105 CFU/g of feed. For HMC, corn kernels (30.1% of moisture) were processed and ensiled in 5-L jars for 44 or 64 d. For RCG, corn kernels were purchased at 14% moisture, ground, and water was added to reach 35% moisture. Afterwards, ground kernels were ensiled in 5-L jars for 21 or 42 d. Measurements included fermentation end-products (acids, alcohols, and NH3-N), microbial counts (LAB, yeasts, and molds), and aerobic stability. Both trials were set up as a completely randomized design using a 2 x 2 factorial arrangement. Data were analyzed using MIXED procedure of SAS, followed by a Tukey test at P ≤ 0.05. In both experiments, inoculated silages had reduced concentrations of lactic acid and greater concentrations of acetic acid and 1,2-propanediol. These three fermentation end products increased over time for both treatments. In HMC, there was an interaction between inoculation and time of conservation for propionic acid concentrations. Also, the concentration of NH3-N was greater in treated silages. In both experiments, the population of LAB was greater in inoculated silages. For RCG, yeast population was greater in CON treatment. During aerobic exposure, treated silages remained more stable in both trials. In HMC, the aerobic stability was > 240 h for treated silages, whereas CON silages had 94 h of stability. Still in HMC, the peaks of temperature were 39.5 and 28.2 oC and the pH values (after 10 d of aerobic exposure) were 6.81 and 4.38 for CON and inoculated silages, respectively. In RCG, the aerobic stability was more pronounced at 42 d of conservation (35 vs 66 h for CON and inoculated silages, respectively). Overall, the combination of L. lactis and L. buchneri modulates corn grain silages fermentation and improves aerobic stability.

PSIII-7 Effects of Saccharomyces cerevisiae fermentation product on total tract digestibility, ruminal fermentation, and plasma metabolome of beef steers fed a finishing diet

Abstract Saccharomyces cerevisiae fermentation product (SCFP) has been widely studied; however, its mode of action on high-concentrate diets has not been fully elucidated. This study evaluated the impact of SCFP on total tract digestibility, fecal excretions of N, P, Zn, and Cu, rumen fermentation, and plasma metabolome of finishing beef steers. Ruminally cannulated Holstein steers [n = 8; body weight (BW) = 580 ± 29.2 kg] were enrolled in a crossover design study with 25-d treatment periods and a 24-d washout period. Steers were fed ad libitum a finishing diet consisting of 20% corn silage and 80% concentrate (on DM basis). Steers were blocked based on initial BW and randomly assigned to two treatments in period 1 and switched to the other treatment in period 2. The treatments were CON (Control, basal diet only) and SCFP (basal diet top-dressed with 12 gּ steer-1ּ ּ d-1 SCFP, NaturSafe, Diamond V, Cedar Rapids, IA). Feed and fecal samples were collected during d 22 to 24 for determination of digestibility. Blood was collected before morning feeding on d 25. Plasma samples were analyzed for metabolome with liquid chromatography-mass spectrometry (LC-MS). Rumen fluid was collected via the rumen cannula at 0, 4, 8, and 12 h post-morning feeding on d 25 and analyzed for pH, volatile fatty acids (VFA), and NH3-N. Performance and ruminal fermentation characteristics data were analyzed using the GLIMMIX procedure of SAS 9.4. Metabolomic data analysis was conducted with Metaboanalyst 6.0. Supplementing steers with SCFP reduced DMI (10.6 vs. 11.4 kg/d, P = 0.05) without affecting (P > 0.05) average daily gain, feed efficiency, and digestibility of organic matter, crude protein, and neutral detergent fiber. Treatment did not affect (P > 0.10) fecal excretions of N, P, Cu, and Zn. Feeding SCFP increased ruminal pH (6.29 vs. 6.01, P = 0.01), numerically reduced concentrations of NH3-N (5.01 vs 6.25 mM, P = 0.16), and total VFA (96.8 vs. 102.5 mM, P = 0.15). SCFP also reduced the ruminal molar proportion of butyrate (11.2 vs. 12.8 molar %, P = 0.01) and tended to increase those of isobutyrate (1.03 vs. 0.90, molar %, P = 0.06) and isovalerate (2.62 vs. 2.29, molar %, P = 0.10). Supplementation of SCFP enriched (P ≤ 0.05) purine metabolism, amino sugar and nucleotide sugar metabolism, and lysine degradation pathways in the plasma. Additionally, tryptophan metabolism and pyrimidine metabolism pathways tended to be enriched (0.05 < P ≤ 0.10) by SCFP. Our findings indicate that feeding SCFP improved the ruminal pH of finishing cattle, which may be beneficial for preventing subacute ruminal acidosis in feedlot cattle. Additionally, SCFP enriched several important plasma nitrogen metabolism pathways, potentially associated with microbial nitrogen metabolism in the rumen, warranting further research.

157 Microbial inoculant effects on limpograss silage

Abstract Warm-season perennial grasses are the main forage sources preserved as silage or haylage by livestock producers in subtropical and tropical regions; however, the nutritive value and silage fermentation parameters are often less than desirable. Microbial inoculants have been used to improve grass silage nutritive value and fermentation characteristics with inconsistent results. The objective of this study was to investigate the effects of a microbial inoculant on nutritive value and fermentation parameters of ‘Gibtuck’ limpograss (Hemarthria altissima) silage. Treatments were silage treated with SiloSolve FC (68.1 billion CFU/g, Lactobacillus lactis and Lactobacillus buchneri) or control (no microbial inoculant) distributed in a complete randomized design with 10 replicates. The inoculant level used was 0.5 g/Mg of forage. The experiment was conducted in Ona, FL in May 2023. Twenty 4 × 4 m plots of established limpograss were harvested at 15-cm stubble height with 58-d regrowth interval. The forage was chopped to a particle size ranging from 10 to 18 mm, placed into mini-silos (PVC pipes with rubber), and sealed immediately. The inoculant was applied with a hand sprayer before ensiling. The silos were opened after 60 d for analysis. There was no difference (P > 0.05) between the inoculant and control treatments on DM concentration (25%), DM recovery (96%), NDF (67%), and NFC concentrations (14%); however, silage treated with inoculant had greater CP (8.5 vs. 8.0%; P = 0.03), IVTD (56 vs. 54%; P = 0.01), and NDFD (53 vs. 51%, P = 0.02) and lesser ADF concentrations (38 vs. 40%; P = 0.02) than control. The inoculant did not affect (P > 0.05) silage pH (4.2) and lactic acid concentrations (1.5%) but resulted in greater acetic acid (2.5 vs. 2.0%; P = 0.01), propionic acid (1.6 vs. 1.0%, P < 0.01), and total acid concentrations (5.6 vs. 5.0%; P = 0.04), and decreased butyric acid (0 vs. 0.2%; P < 0.01), isobutyric acid (0.1 vs. 0.4%; P < 0.01), and NH3-N concentrations (4.4 vs. 5.3% N; P < 0.01). Aerobic stability (140 h), mold (1.1 log cfu/g) and yeast (2.2 log cfu/g) count were not affected (P > 0.05) by the inoculant treatment. At the genus level, there was no difference (P > 0.05) in relative abundance of Lactobacillus (85%), Enterobacter (4.0%), Enterococcus (1.8%), and Weissella (0.2%) between inoculant and control, but silage treated with inoculant had less Clostridium (1.0 vs. 2.3%, P = 0.04), Pediococcus (0.2 vs. 0.3%, P = 0.03) and greater relative abundance of Lactococcus (2.8 vs. 0.5%, P < 0.01) and Bacillus (0.2 vs. 0.1%, P = 0.01). At the species level, the inoculant was effective to increase the relative abundance of Lactococcus lactis (from 0.02 to 0.48, P = 0.002) and Lactobacillus buchneri (from 1.4 to 1.9, P = 0.03). SiloSolve FC is a promising microbial inoculant to be used in warm-season grass silage in subtropical and tropical regions.

Effects of LED lights and cytokinin on the phytotreatment of simulated swine wastewater by Azolla spp.: Pollutant removal and biomass valorization

Phytoremediation is an eco-friendly and affordable option for tackling wastewater pollutants. The study focused on how light-emitting diodes (LED) light exposure, measured by intensity and duration (photoperiod), along with cytokinin, impacts Azolla microphylla's simulated swine wastewater treatment performance and biomass production. Under optimal treatment conditions, high removals of COD (89.2 % to 90.8 %), N-NH4+ (72.6 % to 91.2 %), N-NO3- (84.4 % to 88.6 %), Cu (75.4 % to 86.4 %), sulfamethoxazole (77.0 % to 79.0 %), P-PO43- (54.1 % to 59.9 %) and DOC (67.4 % to 71.3 %) while Zn presented a more moderate reduction (2.0 % to 9.7 %). Biomass productivity reached up to 34.8 t ha-1 yr-1. Protein production accounted for 23 % to 27 % of dry weight, while lipids ranged from 20 % to 34 % of dry biomass. Carbohydrate content varied from 8 % to 28 % of fresh weight. Higher light intensities, with both high or low values of photoperiods, and low concentrations of cytokinin were identified as optimal conditions for removal of almost all pollutants. However, pollutant removal was impacted differently by LED light and cytokinin concentration. In treatment conditions with the shortest photoperiods (8 h), the lowest residual Cu and Zn concentrations, whereas with longer photoperiods (24 h), the lowest residual concentrations of N-NH4+ and P-PO43- concentrations were recorded. On the other hand, SMX was the only parameter in which cytokinin had a clear influence on its removal, with the lowest residual concentration observed under 8-hour photoperiods combined with the lowest tested cytokinin concentrations (0.3 mg L-1). For residual COD and N-NO3-, no discernible pattern was evident for any of the analyzed factors. Therefore, the study demonstrates the potential for treating simulated swine wastewater using Azolla microphylla, aligned with its ability to produce biomass rich in high-value compounds.

Drought reduces nitrogen supply and N2O emission in coastal bays

Severe droughts are increasingly prevalent under global climate change, disrupting watershed hydrology and coastal nitrogen cycling. However, the specific effects of drought on nitrogen transport from land to sea and subsequent nitrogen dynamics remain inadequately understood. In this study, we evaluated the consequences of the 2020–2022 drought on nitrogen supply and N2O emissions in Xiamen Bay, Southeast China. The results showed that drought significantly reduced annual NH4N, NO2N, and NO3N concentrations in Xiamen Bay by 49.4 %, 32.1 %, and 40.3 %, respectively, compared with the pre-drought year of 2019. The decline in NH4N concentration was mainly attributed to reduced surface runoff across all seasons. NO3N and NO2N concentrations declined only during spring and summer, primarily due to increased potential evapotranspiration (PET) hindering nitrogen supply via groundwater and concurrently enhancing land denitrification. Annual N2O emission from Xiamen Bay decreased by 40.0∼72.7 % during the drought, highly correlated with the decline in the concentrations of NO3N, DIN, and DTN (p < 0.001). Comparative analysis revealed that NO3N concentration exhibited consistent negative linear regressions with PET and declined as evaporative demand drought conditions worsened across Xiamen Bay, Sansha Bay, and Chesapeake Bay throughout 2010–2022. NH4N concentration showed a positive regression with river discharge in Xiamen Bay, but negative regressions in the other two bays. Our results indicates that drought reduces N2O emission primarily driven by nitrate substrate reduction in the bay. This study provides new insights for predicting coastal nitrogen dynamics and greenhouse gas emissions under global environmental change.

Effects of 5-Aminolevulinic Acid Supplementation on Gas Production, Fermentation Characteristics, and Bacterial Community Profiles In Vitro.

To investigate the effect of 5-aminolevulinic acid (5-ALA) on in vitro rumen gas production, fermentation characteristics, and bacterial community profiles, five levels of 5-ALA (0, 100, 500, 1000, and 5000 mg/kg DM) were supplemented into a total mixed ration (concentrate/forage = 40:60) as substrate in an in vitro experiment. Results showed that as the supplementation level of 5-ALA increased, asymptotic gas production (b) decreased linearly and quadratically (p < 0.01) while the dry matter degradation rate increased quadratically (p < 0.01). Meanwhile, the propionate concentration of 72 h incubation fluid increased linearly (p = 0.03) and pH value increased linearly and quadratically (p < 0.01), while the concentrations of butyrate, isobutyrate, valerate, isovalerate, and NH3-N and the ratio of acetate/propionate (A/P) decreased linearly and quadratically (p < 0.05). There was no significant difference in any alpha diversity indices of bacterial communities among the various 5-ALA levels (p < 0.05). PCoA and PERMANOVA analysis revealed that the bacterial profiles showed a statistical difference between the treatment 5-ALA at 1000 mg/kg DM and the other levels except for 5000 mg/kg DM (p < 0.05). Taxonomic classification revealed a total of 18 and 173 bacterial taxa at the phylum and genus level with relative abundances higher than 0.01% in at least half of the samples, respectively. LEfse analysis revealed that 19 bacterial taxa were affected by 5-ALA levels. Correlation analysis showed that Actinobacteriota was positively correlated with the gas production parameter b, the ratio of A/P, and the concentration of butyrate, isovalerate, and NH3-N (p < 0.05) and negatively correlated with pH (p < 0.05). WPS-2 exhibited a negative correlation with the gas production parameter b, the ratio of A/P, and the concentration of butyrate, valerate, isobutyrate, isovalerate, and NH3-N (p < 0.05), along with a weaker positive correlation with pH (p = 0.04). The Bacteroidales BS11 gut group was negatively correlated with the concentration of propionate but positively correlated with gas production parameter b and the concentration of butyrate and NH3-N (p < 0.05). The Lachnospiraceae NK3A20 group was found to have a positive correlation with gas production parameter b, the ratio of A/P, and the concentration of butyrate, isobutyrate, isovalerate, valerate, total VFA, and NH3-N (p < 0.05), but a highly negative correlation with pH (p < 0.01). Differential metabolic pathways analysis suggested that metabolic pathways related to crude protein utilization, such as L-glutamate degradation VIII (to propanoate), L-tryptophan degradation IX, and urea cycle, increased with 5-ALA levels. In summary, including 5-ALA in the diet might improve energy and protein utilization by reducing the abundance of Actinobacteriota, the Bacteroidales BS11 gut group, the Lachnospiraceae NK3A20 group, and certain pathogenic bacteria and increasing the abundance of WPS-2.

Co-composting of tail vegetable with flue-cured tobacco leaves: analysis of nitrogen transformation and estimation as a seed germination agent for halophyte.

Resource utilization of tail vegetables has raised increasing concerns in the modern agriculture. However, the effect and related mechanisms of flue-cured tobacco leaves on the product quality, phytotoxicity and bacterially-mediated nitrogen (N) transformation process of tail vegetable composting were poorly understood. Amendments of high-dosed (5% and 10% w/w) tobacco leaves into the compost accelerated the heating process, prolonged the time of thermophilic stage, increased the peak temperature, thereby improving maturity and shortening composting duration. The tobacco leaf amendments at the 10% (w/w) increased the N conservation (TN and NH4-N content) of compost, due to the supply of N-containing nutrient and promotion of organic matter degradation by tobacco leaves. Besides, tobacco leaf amendments promoted the seed germination and root development of wild soybean, exhibiting the feasibility of composting product for promoting the growth of salt-tolerant plants, but no dose-dependent effect was found for tobacco leaf amendments. Addition of high dosed (5% and 10% w/w) tobacco leaves shifted the bacterial community towards lignocellulosic and N-fixing bacteria, contributing to increasing the compost maturity and N retention. PICRUSt 2 functional prediction revealed that N-related bacterial metabolism (i.e., hydroxylamine oxidation and denitrifying process) was enhanced in the tobacco leaf treatments, which contributed to N retention and elevated nutrient quality of composting. To the best knowledge, this was the first study to explore the effect of tobacco waste additives on the nutrient transformation and halophyte growth promotion of organic waste composting. These findings will deepen the understanding of microbially-mediated N transformation and composting processes involving flue-cured tobacco leaves.

Impact of winter coverage crops and nitrogen fertilization on soil respiration and nitrogen mineralization in no-tillage systems

Microbiological activity in soil is crucially important to maintaining soil quality. Soil is sensitive to management practices, and microbiological activity plays a crucial role in processes like transforming organic N into inorganic fractions. The objective of this study was to assess how winter coverage crop residues influence soil respiratory activity and N mineralization during successive corn crop developments under a no-tillage regime. We employed a randomized block experimental design with subdivided plots and three replications. The main plots comprised various coverage crops (Black Oats, Ryegrass, Rye, White Lupin, Common vetch, Turnip, consortia of Oats + Vetch and Oats + Vetch + Turnip, while subplots received doses of N-mineral (0 and 180 kg ha-1) during the corn growth stage. We evaluated the respiratory activity of microorganisms and levels of inorganic N in the soil throughout the corn crop cycle. The consortia of coverage crops exhibited distinct responses in respiratory rates, with Oats + Vetch having superior results compared to Oats + Vetch + Turnip. We observed positive responses in nitric N (N-NO3-) due to the mineralization of common vetch residues within the first fifteen Days After Sowing (DAS). However, N-mineral doses from nitrogen fertilization during the corn coverage age phase did not alter the respiratory of the microorganisms nor did it alter the concentrations of N-NH4+ in the soil. Mineral fertilization resulted in the immediate availability of N in the form of N-NO3-.

Tailor-made ammonia nitrogen risk management with machine learning models for aquatic environments in the Mainland of China

Efficient management of pollutant risks in water bodies is crucial for public health and aquatic ecosystem sustainability. However, the toxicities of pollutants, such as ammonia nitrogen (NH3-N), are often affected by multiple water quality factors, including the pH and water temperature. Extensive spatial and temporal variability in these factors hinders tailor-made management of risk. This study used high-frequency monitoring data collected over 1 year to evaluate the long-term NH3-N risk in China’s aquatic ecosystems. High accuracy and interpretability were achieved by decomposing NH3-N risk into the contributions of key influencing factors using random forest models and Shapley Additive Explanations. Two distinct types of NH3-N risk hotspots were identified across 18 cities: 15 cities with high NH3-N concentrations and 3 cities with low environmental carrying capacity due to high pH levels or elevated water temperatures. For the former, rapid NH3-N abatement measures are necessary to bring NH3-N concentrations back below the environmental capacity. For the latter, it is recommended that NH3-N related industries are relocated to regions with high environmental capacities because fragile environments are not suitable for such industries. Importantly, this study investigated methods for attributing pollutant risks in the context of non-linear influencing factors, and the risk of NH3-N was predicted to increase by 6.1 % by the end of 2100 in the context of increasing temperatures under the SSP 2–4.5 scenario. The methodology is also adaptable and suitable for integration into global ecosystem risk management efforts to balance development and aquatic ecological sustainability.